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Why are fighter pilots seated and not reclined?
I have always wondered about this one.
Pulling high G-forces is, I assume, the most physical challenge the pilot of a high performance fighter aircraft needs to be able to sustain without blacking out or worse. Indeed, in most countries in the world would-be fighter pilots cannot qualify for jet-jockey status without first passing the dreaded centrifuge test.
Further, modern jets can in fact pull much higher G-forces than the pilot without damage to the aircraft. Indeed, I read somewhere once that one of the issues with auto-missile-avoidance systems is that the aircraft is limited to performing maneuvers that the pilot can withstand.
As I understand it, the issue with high-G turns is that the blood is drained or driven from the body to the lower (and upper when undergoing high negative-G) extremities of the body resulting in starvation of the brain and consequent blackouts or even embolism in the negative-G case.
I realize pilots wear tight G-suits which have air pumped into them to restrict the amount of blood that can accumulate in their lower extremities, but that doesn't reduce the stress on the heart trying to pump blood up to the head.

It seams rather obvious to me that much of the issue with high-G is caused by the seated position of the pilot. It is an established fact that the more vertical you are the harder it is to withstand G-forces.
Why then are modern jets not designed with the pilot in a more reclined position? For example, the position used by Formula-1 race car drivers:

Don't get me wrong, I understand F-1 drivers do not need to withstand the same kind of sustained vertical forces that a fighter pilot does, however the legs-up reclined position seems to be far more practical for a high-G environment.
I do realize that the whole ejector-seat mechanism would need to be redesigned to eject the pilot differently, and that the pilot's ability to see behind himself would be compromised without technical aids, but surely the increased turn rates and lower profile cockpit would outweigh those issues.
NOTE: I have seen other posts on using the head first "prone" position, including this stack-exchange link but nothing on reclined.
ADDITION: Found this image of a Foka-5 glider pilot position too... note how wonderfully streamlined it is.

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Fighter pilots are far more reclined than you might think.
But seat angles are limited by the need for good visibility.  Pilots frequently need to look to down-and-sideways, down-and-forward, and towards their back-quarters.  These are angles that your F-1 Driver couldn't possibly see.
Also, High-G maneuvers are quite rare.  Most modern military planning is about making sure pilots are never even in a position where they need to evade a missile or dog-fight another plane.

Yup as I mentioned, I realize that, but with modern fighter helmets with camera vision systems, that should be a fairly minor technical issue.

The helmet / camera systems are not available on most airplanes.  The F-22 might be the only plane that has a fully-featured system.  The F-18 was created in 1983 (when digital cameras and advanced processing was completely unheard of).

@abelenky doesn't the F-35 have a fully featured system?

I believe the F-35 is still under development.  When complete, it should have a full head-mounted display system, but nothing on that project has gone according to plan.

"Most modern military planning is about making sure pilots are never even in a position where they need to evade a missile or dog-fight another plane. " doesn't that make the need to look over your shoulder less of an issue not more.....

Pilots look over their shoulder for such mundane things as: "How far away is that runway?" "Which town/road/landmark am I passing?" and "Did my bomb just hit the target?"

As a note about camera vision systems, the F-22 doesn't have one. It also doesn't have a helmet mounted display required to use one.
The F-35 does have one, it's fully functional and has an operational HMD. The camera system is called AN/AAQ-37 Distributed Aperture System (DAS), if you do a quick google you'll find plenty of demonstration videos.

Wouldn't an over-reliance on the digital mounts just cause other issues anyway? With the current seating position, if the electronic display fails, the pilot is still able to physically look, right? If they are reclined too much & the display fails, they have no manual backup?

@Obsidian If the electronics fail in a modern fighter jet the pilot can only hope that they can eject manually, because they certainly couldn't fly it anymore. And the chances of just the display failing without reason seems negligible.

The F-16 in fact has a relatively large recline (compared to other fighters). From the main F-16 Wikipedia

The F-16's ACES II zero/zero ejection seat is reclined at an unusual tilt-back angle of 30°; most fighters have a tilted seat at 13–15°. The tilted seat can accommodate taller pilots and increases G-force tolerance; however it has been associated with reports of neck ache, possibly caused by incorrect head-rest usage. Subsequent U.S. fighters have adopted more modest tilt-back angles of 20°. Albano, J. J. and J. B. Stanford. "Prevention of Minor Neck Injuries in F-16 Pilots". Aviation, Space and Environmental Medicine Issue 69, 1998, pp. 1193–1199.

From this archived DTIC Article from 1962 it appears to confirm a lot of what the other answers said. As noted in the comments this in regards to the prone position and not a reclined position. From the summary page:

The prone position of the pilot in high-speed airplanes has certain advantages
  (higher g-tolerance of the pilot, reduction of drag due to decrease of frontal
  area, improved instrument visibility) and drawbacks (narrowing of field of
  vision, decrease of visual acuity, aggravation of claustrophobic tendencies,
  discomfort encountered in this abnormal position).

Spacecraft routinely have their pilots in the  reclined position but their main objective is a fairly narrow scope compared to a fighter pilot. It seems the wrap-up answer is that other positions are useful in the context of the specific mission of a given platform but for military aircraft it doesn't seem to offer an advantage.

Note that specific article quote is about prone positions, whereas the OP's question is specifically about supine positioning (as in the F1 and glider examples). The article does explicitly distinguish prone and supine.  Prone crew positions are rare in actual aircraft, except maybe some WWII bomb aimers, and the Wright brothers...

Note that prone != reclined. Prone means on your stomach - and spacecraft rarely have their pilots in the prone position. The two common ones I know of for spacecraft is seated (reclined or otherwise) or standing (like the lunar lander).

A prone flying position was tested on a Meteor aircraft http://www.diseno-art.com/encyclopedia/strange_vehicles/gloster-meteor-f8-prone-pilot.html

thanks, edited to address the comments. I thought of this last night as I'd routinely hear prone in reference to a laying down rifleman not a reclining rifleman (which seems a lot more comfortable though probably harder to point down the battlefield)

A pilot position as reclined as pictured would have the pilot upside down with blood rushing to the head whenever the plane is in a steep fast climb such as takeoff and many dogfight maneuvers.
Probably not a great position for maintaining orientation and consciousness.
It feels natural to move forward while seated upright.
Even climbing vertically is a similar G sensation pressing you into your seat.  But people are not accustomed to being dragged skyward by the feet.
A very critical device in a F1 car that allows for that extremely reclined position is the HANS head and neck restraint system.  Without it, the inertia of a helmeted head would carry the head forward causing grave injury in a crash, and to a lesser extent during hard braking.  The reclined position starts you out closer to the limit of your safe range of motion.  HANS prevents you from reaching that limit, but it also prevents you from looking down.  That can be a useful skill if you are the type of pilot that likes to.. uh... land.  A HANS type device isn't required in the glider pictured because it lacks the capability to rapidly accelerate or decelerate, thus leaving the pilot free to look around.

is slomobile a sock puppet of user22253? Looks like they have same avatar. BTW interesting answer

Probably, he created a named account, but either didn't know how to convert the existing account or something went wrong. @slomobile, you can ask a moderator (or maybe a Stack Exchange employee) to merge the two accounts if you care about your existing rep points.

"A very critical device in a F1 car that allows for that extremely reclined position is the HANS head and neck restraint system." Not true. The HANS system is to prevent injury. It didn't existed before 2003. But pilot seating has been very low for a long time.

"But people are not accustomed to being dragged skyward by the feet." If you are going up it would not feel that way... you would definitely be pressed into the seat back... and would feel like you were accelerating.

Re "It feels natural to move forward while seated upright."  I don't think so.  At least there are many individual differences.  I feel much more comfortable in the semi-reclined posture of sports cars or gliders than in the bolt-upright posture of SUVs or my Cherokee.

I'm 100% with you, @jamesqf, however, no sports car and probably no glider can climb the way a fighter can, so it's probably not quite a fair comparison. Nor is the comparison to the F1 driver's positioning in the OP.

@FreeMan: I don't think climbing ability is the right way to think about this.  Instead, it's acceleration and the axis along which the acceleration acts.  Per Google, an F1 car can accelerate at about 2g (but brake at 5g and pull 4-6g in cornering).  I can't find actual figures for jet fighters, but AFAIK few can manage to accelerate in a vertical climb, so straight-line acceleration would be a bit over 1g.  (Carrier catapult launches around 4g.)  The high g forces come in turns, so would act parallel to the body axis for seated, perpendicular for prone.

@jamesqf - I wasn't referring to the G-force, but the actual angle of climb. If a C-172 was climbing at a leisurely rate, but the pilot were reclined, his feet would be at or above his head with the F1 seating position. This would lead to the blood pooling in the head and the resulting discomfort, etc. This is the exact opposite of what fighter pilots experience with the current seating position when doing high positive G maneuvers and the blood pools in the lower extremities (hence the use of a G-suit). Probably easier to have a g-suit acting on the legs than the head. ;)

@FreeMan: In my experience, the C-172 climb angle isn't all that much different than e.g. climbing mountain roads in a Miata (or my previous British sports cars).  The thing is to look along the axis of acceleration: in a upright seated position, there's about a 4 ft distance between head & feet, in a semi-reclined one, less than half that, so less pooling.

@freeman excellent point - I ride a recumbent bike, and that puts my feet just below my heart level.  When on a long ascent my feet are at shoulder level or higher, and go numb after an hour or so.  And there's exactly 1G involved here, it would be far worse under jet acceleration.

This question is pretty similar to this one but you provide a slightly different position so there may be some variances. Some things to consider,

In the F1 like case, blood would still have the ability to pool in the gluteal region as well as the feet since they are lower than the head.
In the more reclined, feet forward position one would need to have the instrument panel over their legs (and a significant amount of it) lest it be quite far and possibly out of reach. This could potential cause a problem in an ejection scenario.

A good, practical example of this position is the Bede Jet a not so popular kit plane famously flown by James Bond.

Yup, issue 2 I assumed more side panel controls including side joy-stick... i.e. a wider cockpit vs tall. Not insurmountable though. Issue 1 true, but still I would think less of an issue than seated, but I could be wrong.

the controls are not whats in the way, its the instrument panel aircraft instrumentation require physical input along with the control surfaces they are not just things to look at.

Yes I know, but they could also, just as easily,  all be at arm reach left and right of the pilot.

They could be to the side, @Trevor, but there's only so much space available exclusively to the side in a cockpit and still within the pilot's reach when pulling high Gs. The other advantage to having controls in front of the pilot instead of to the side is minimum time with eyes inside the cockpit to ensure that the right switch is being operated and/or confirming switch settings.

Bede Jet not so popular? :) You may not be aware of this, but some 40 years later there are companies still producing them and they have a waiting list. The most well known is http://www.bd-micro.com

The Recline  was to get the seat in the jet... that is the primary reason.
On long ferry missions not much pressure is on your sit bones and back.
G tolerance and endurance is about hitting the gym.. not really the 30 degrees of recline :)
Also ejection out of the jet.. which can be career ending... your knees have to clear that dash on the way out... so  they had to make sure the seat gets you clear of the suns-shield /dash and the vertical tall as you are fired toward it...

Yes I realize the classic ejection method would not work..but if you are going to redesign the entire cockpit that would all be part and parcel of it. See my latest comment on the main question.

Ahh ok.. Well the B1 has a ejection pod... the Su-27 series as well as the MiG 29 series as well as the F-35 have auto eject systems on the jets. In the Case of the 27-35 the Ekron determines when the jet is not viable and pushes the pilot out.. the F35 uses a similar system but it is because the eject angle is critical due to the the way the cockpit opens

Cockpit design back during the Fighter Mafia days was a brutal process... Engineers want one thing, the Military leadership wanted something else... Stuff like in cockpit fuel shut off and breakers can be placed in places that make no sense... so a lot of factors go into it.. also when you are being shot at you don't want any buttons or switches in areas that will degrade the jet or it's system... that's why some stuff is places in odd spots...

Yup..always the way,,,

True..it also doesn't help that the requirements change a lot from inception to delivery.... "OH.. didn't we mention we we need this interceptor to do ground support too...!"

yeah.... the good old days of the single role fighter are gone... if you compare the the A-7 Corsair II to the F-16 you can really see how  early block F16 air to ground mode is almost a direct software copy of the A7.

This answer is very hard to understand.  Re "The Recline was to get the seat in the jet... that is the primary reason."  Which "jet" are you speaking of?  Please specify.  If the F-16, are you asserting that the reclining seat was chosen more to minimize the cross-section than to increase pilot's G-loading tolerance?  What is your evidence for this?  Re"On long ferry missions not much pressure is on your sit bones and back." Are you saying this is true because of the reclined seat, or just that it's true in general and thus there's no reason to adopt a reclined seat to help w/ these issues?

(Ctd)  Re "Also ejection out of the jet.. which can be career ending... your knees have to clear that dash on the way out... so they had to make sure the seat gets you clear of the suns-shield /dash and the vertical tall as you are fired toward it... " -- this sentence is pretty much incomprehensible if you don't tell us which plane you are talking about.  Anyway it appears you are talking about some aircraft in which these design goals were able to be met despite a reclining seat position-- so how it's not clear how this part of the answer is relevant to the question.

(Ctd) It's unclear whether you are saying that the reclining seat position in this case (whatever aircraft we are talking about) helps or hinders w/ clearance with the sun shield during ejection.  (I'm pretty sure you were speaking of an aircraft flown on this planet, hence "sun" should be singular.)  ;)

Simple Answer: Because F1 drivers do not need to look beneath the car or eject from it.
There are many things that are more important than withstanding G-forces in a fighter jet. Amongst these is the ability to have good downward visibility on the terrain. This is why all the newer jets (after the F-16) favor a taller and more upright seating position. Also, if the pilot is lying almost flat on his back it is rather hard to eject from the aircraft without either losing the limbs or having to first jettison the instrument console in front of him.

The ejection problem is rather that the ejection would have to be at the same angle and thus be far more likely to intersect the path of the vertical stabiliser, with predictable results to the pilot's body.

Simply put, because fighter pilots need to look around. If you're reclined too far, and you need to "check your six", it becomes an impossible task. A reclined position does minimize the effects of g-forces, but it also negates the ability to see all around you in 3D.


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What are those things at the wing tip of an aerobatic aircraft?
See:

The radially placed needle-like things that resemble a snowflake in the first picture.
The triangular structure in the second picture.
In the third picture, the object placed on only one wing
In the last one, it's also placed on one wing but this one is perpendicular.

What are those things?

they look aligned with the head of the pilot. so I guess some kind of reference. Welcome and nice first question, btw!

They allow you to judge the angle of the horizon while watching your outside reference. Acrobatic pilots very rarely spend a lot of time looking at instruments.

@ymb1 "They" as in the pilot, not the attitude sights (I know you understand that from your answer, just clarifying for others).

@ymb1: Too bad David didn't think to cage the AI before venturing out.

Nice. I never thought my question would go that much popular. After some time being the member without asking or answering any question, my first question becomes hit. It's nice. To be honest I don't think my question that much interesting.

They are external attitude references. They're aligned with the aircraft's axes and positioned along the pilot's line of sight to give a quick visual guide to the aircraft's attitude during aerobatic maneuvres.
You can see the alignment more clearly on this photograph

it seems right. but it would great if you provide some links for reading. an article would useful for understanding how pilots use this things to see attitude.

@hfc Google "wingtip aerobatic reference" and you'll see lots of this subject.

You don't see those except on serious aerobatic airplanes.  In competition aerobatics such as those sanctioned by organizations that put on the National Aerobatic Championship and others worldwide, the scoring systems are largely organized around rating the pilots for how meticulously they perform aerobatic maneuvers.  If a pilot does a eight point roll, they want to see clean pauses at every point 45, 90, 135, and so on.  A good pilot will be very precise about the angle and make the maneuver look as though performed by a robot with perfect positioning and timing.  Sloppy maneuvers lose points.  It's not a daredevil competition, more like ice skating in how precise and graceful a maneuver is made.
The horizon (the line where the sky meets the ground) is typically the most used visual reference point for all pilots flying under visual flight rules and those flying aerobatic maneuvers.  It's used to determine the airplanes attitude relative to the ground(pitch, roll, and yaw about the three axis that the airplane rotates around).  As an example, an aerobatic pilot in competition who performs a loop will be judged on how round the loop is (not egg shaped), whether his wings remained level relative to the circumscribed arc that he traverses during the maneuver, and other elements.  If he drops a wing, it makes the maneuver look sloppy.  He determines if his wings are level by observing the relationship of the tips of the wings to the horizon, his only easily identifiable external visual reference.  Dropping a wing will cause one wing tip to be in the dirt below the horizon while the other will be in the sky above the horizon.  Those sights give him more accuracy for determining just exactly where his wings are so that his maneuver looks clean to the judges.  It might not seem like it would be difficult to tell if one wing is low and the other high and it isn't when your flying straight and level.  When your upside down at the top of a loop, it's a lot harder because your focused on maintaining airspeed and staying under g limits so that you don't stall and fall out of the top.  Or, your focused on setting up for a snap roll on top or some other maneuver that requires wings to be level when you exit, otherwise,  you kind of fall, stall, or slop out of the thing and it turns into the equivalent of a 6 g belly flop instead of a loop with a snap on top.  That loses points in competition and in rare cases, breaks wings off airplanes.  Airspeed can hit never exceed limits very quickly when your full power upside down over the top and then fail to pull the g's you need to get through the backside quickly enough.
Good aerobatic pilots make it look easy but it's actually very difficult to perform an aerobatic maneuver precisely.  Most aerobatic students can get the plane over the top of a loop without pulling the wings off on the backside.  Not making it look like a big, sloppy mess is an entirely different story.  It's like precision ice skating while pulling 3g's, or 4,5, or more if you do it wrong usually.  It takes a lot of practice and attention to detail to do it gracefully.

While the information here is useful, it is not an answer to the question but it is posted as an answer.

@kevin From my perspective this answer addresses the question and provides additional information rounding out the answers already given. I would consider this to be a valid answer.

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Is excess fuel leaking normal during take off of a B737?
When we look over this video

it's noted that some fuel is coming off from the left wing during the rotate. This is the position of the fuel vent within the wing, of course, 'leaking' due to new vertical and horizontal forces combined which, in turn, force fluids backwards and outwards in a swept wing, so not exactly a fuel dump procedure as published. My question is: is normal or correct for an airliner to have such an excess of fuel causing it to reach the fuel vent until it spills during take off? Shouldn't this wing carry less fuel?
EDIT: To help explain exactly what I am talking about, we are looking for a very thin trail of fuel coming from the fuel vent of the left wing. This vent is located under the wing and a little ahead the (left) aileron. We are not talking about a vortex from the engine vortex generators or from the flap edges. ;)
This:
This other video shows the same with much more detail:

No no, we are talking about the trail coming under and ahead the left aileron. It is fuel coming from the fuel vent, apparently on a overfueled wing.

Fuel dumping is different to fuel venting. All big jets have fuel vents because in hot temperatures fuel expands and needs to go somewhere. Given that fuel is measured in weight rather than volume it is possible to 'overfill' it. The second video looks like it could definitely be fuel venting. How much venting is acceptable? That's a good question.

At first it looked like a vortex from the wing but looking the videos the second is clearly a leak and the first is looks likely a leak. Happens I know the first video airport and that town is hot tropical (almost equatorial) so @ben comment makes a lot of sense. It's common the tanks are filled at night and overfilled with the expansion at a warm morning

"Excess" fuel leaking, by definition, is not normal. ;)

@sgroves Not true.  For example, during a fast taxi, fuel may overflow into the surge tank then be vented.  It is not "by definition" abnormal.  It's also common for a full tanks operation to result in some spillage, again, perfectly normal.

Multiple comments and answers effectively saying "no", because there is no fuel dump system.  There are many reasons for fuel to vent from a wing other than fuel dump.  Whether this particular case is a fuel spill or just condensation and, if the former, whether it's normal or not is difficult, if not impossible, to say with the videos presented.

@Simon I was just commenting on the use of the word "excess". If fuel leakage is normal, there was by definition not excess fuel leakage. There was the expected amount. It was a poor joke, I suppose.

@sgrovrs Ah,  ok.  But even without an overfill the surge tanks can vent.

No it is not normal. It can happen if the wing tanks are fully filled, typically for long trips or when the airline is tankering fuel to airports where fuel is more expensive. When cold fuel warms up it expands. With full tanks, the fuel has to go somewhere and it flows through the vent channels and will end up in the surge / vent tanks in the wing tips. From here the fuel can flow back into wing tanks (when there is space again) through a check valve.

 Boeing 737 fuel vent system. Source: Aeronautics guide
There is a little NACA duct at the underside of each wingtip (about a meter from the tip) in the surge tank. That ensures a positive pressure in the surge tank and through the vent channels in the fuel tanks. This help the fuel pumps, reduces evaporation of the fuel and prevents a vacuum when the fuel is being used.

source: www.b737.org.uk
If the wing tanks are overfilled, this is where the fuel will come out.

source: the aviation forum: user Keithnewsome
During the take-off the fuel tanks are changing their shape a little bit because the wing is flexing up. This may slightly reduce the volume of the tanks so if they are fully filled you will see a fuel trail spilling from the fuel vents at take-off.
Another situation where this may occur is at zero-gravity. I have seen this many times during parabolic flights with a Cessna Citation. At zero gravity the fuel will start to fly around in the tank and it will find its way to the exit (the vents at the wing tip) resulting in an impressive cloud of fuel from the wingtips. Whilst it looks like a big cloud, it is actually very little fuel that is lost.

In the video, you see the fuel trail starting below the wing (at 1:28), a couple of seconds into the 0-G part of the flight.

The fuel trail shows at 2:50 :)

@orique Yes, at 2:50 again. The first time it is visible is at 1:28.

Ah! I was seeking for the moment and just found the one at 2:50. Thanks!

Fascinating stuff.  As I understand it, the fuel tanks on some vehicles are not actually "empty", but are filled with some kind of open-cell foam or mesh (I believe the two reasons are (a) prevent sloshing (b) prevent fume buildup? ) In fact are the tanks on large airlines just "empty" or do they have  this type of foam/mesh guts?

@Fattie the answer can be found elsewhere on the site. Though airliners use subdiving of tanks and baffles, I believe the sponge would be too heavy and reduce usable fuel too much

Lots of interesting information coming from this observation and it makes me smile.
Ok, quick logic check; if fuel can come out the vent during flight, what will happen to fuel ballance? If the aircraft, and in this case, banks to the left, won't the fuel, that is still in the tip of the wing run out the vent?
Short explanation on how the vent works and this is for automatic pressure refueling. The vent only opens during refueling.  This is done by a sense pressure line that is taken off the main refuel line. What this does is it opens the vent valve to let the air out of the tank otherwise the tank would blow up like a balloon. Once refueling is stopped at the required level the vent closes.
Ok, let's say the refueling does not stop automatically because there's a problem.  The fuel system has what is called High Level Sensors that stop the refuel process when the tank get to max level.
If both of these systems fail then, yes, the fuel will come out of the vent but, this only because there is still pressure from the refuel line on the sense line keeping it open. This is also a safety precaution. Ones the refueling is stopped, the vent valve will close.
The NACA duct let's air into the tank to prevent a vacuum from forming due the fuel being sucked out by the fuel pumps. It has one way valve in it to prevent fuel from running out.
Next; wing fuel tanks. Ribs form the shape and structure of the wing, leading edge to trailing edge ( front to back). Inside the wing the ribs also act as baffles but, not all of them though. The aircraft manufacturer designe the tank inside so it looks like compartments. Each compartment is connected to the next with one way flapper valves. So basically the fuel can only run towards the fuel pumps and not back again. This ensures there's always a positive feed towards the pumps even is the aircraft banks to one side.
So looking at all the above info, the problem with the fuel coming  out of the vent  was a faulty vent valve that didn't close as it should have. This would have been rectified before the next flight. And by the way, this isn't the first time this happened.

What you see is not actually fuel. It is the vortex coming off an engine strake in which some water vapour in the air condenses. You can see more of that phenomenon in this answer.

Hey, mate: we are talking about the discrete trail coming off under and ahead the left aileron.

@user18674 The trail is coming from over the wing...

I'm talking about this: https://s18.postimg.org/yvvd5dha1/DUBT.png

I have to agree with the OP, that does not look like a condensation vortex.

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Why is the Cumulonimbus cloud formation so dangerous?
I once heard my pilot friend say that it's really dangerous to fly near any Cumulonimbus cloud formations... Something about that it could drag the plane into it.
Cumulonimbus :

Why is it so dangerous?
How is it created?

They are also called thunderclouds when you are below them.

Updraft, scary. Just looking at that thing gives me the creeps. Go in there and you get wrung like a wet washcloth.

Which one is more fun, being struck by lightning, or having a football-sized lump of ice come through the windscreen? Or is it the updraft?

Here's what it's like one-on-one without a plane for protection:    http://www.businessinsider.com/the-survival-story-of-the-only-known-person-to-parachute-through-a-thunderstorm-2013-1

@TylerDurden And not only updraft, but strong downdrafts, and erratic switches between the two.

Just look at it.  It's natures sign post equivalent of "Do Not Enter"...

A cumulonimbus cloud (CB) is dangerous because of the processes occurring in them.  At a minimum you will have an updraft and a downdraft containing rain.  The particular CB you posted in your picture is typical of severe convection.  The anvil is spreading out along the tropopause and there is significant overshooting tops over the anvil.  This indicates the updraft in this cloud is very strong and there is a lot of energy in this storm.  A storm like this likely has hail near the updraft, very strong winds both up and down and severe turbulence within the interface between and around the strong up/down drafts.  There can also be very active in-cloud lightning as well as cloud-to-ground discharges.
Threats near the storm are turbulence, lightning, large hail and significant downdrafts (e.g. microbursts).  Threats within the cloud are severe turbulence, very strong updrafts (some as high as 100 m/s or more) and downdrafts containing torrential rain, hail and lightning.
To better illustrate the magnitude of vertical winds, here is a quick plot from a modeled storm I am working with.

In this plot the reds are updraft and blues are downdraft with the scale on the right in meters/second.  The plot covers 20 km x 20 km area at a height of 5.4 km, which is close to 18,000 ft or 500 mb.  This corresponds to the main updraft in a supercell and you can find areas where less than 5 km cover a vertical wind gradient of 50 m/s.  If you were penetrating this at any decent airspeed you would be in for a very rough ride.
 This storm only had 1800 J/kg CAPE and updrafts can be much faster than this.

CB clouds are (typically) realized from a release of convective available potential energy (CAPE), which is simply a measure of how much warmer a parcel rising from the surface is than its surroundings as it rises.  In an environment that is favorable for convection (CAPE, vertical windshear) where there is ample moisture and a mechanism to force parcels to rise to their level of free convection you can end up with a CB cloud.  A CB is simply a cumulus cloud with rain falling out of it and whether this is a small rainshower or a severe rotating supercell is determined by the environment the storm occurs in.

It's not just "near" them that can be a problem. Near to the airfield where I trained in the UK is a big flat expanse called Salisbury Plain.  Summer storms with CBs were common.  I've experienced strong downdrafts at ground level 5 miles or even more from a storm, strong enough to overcome the lift available to a light helicopter.  It feels like a sudden, strong, cold wind, blowing directly downwards. It's cold because the rising convection currents have carried moist air to the upper atmosphere where it cools, spills over the top then falls back to earth. In a light aircraft, stay well away.

@Simon are you sure it was coming from directly up?  It sounds more like a gust front generated from the thunderstorm outflow, cold because of evaporative cooling.  If upper level air did descend directly down to you from upper tropospheric levels it would actually be quite warm due to adiabatic compression.

Yep.  It would come directly down then of course spill outwards.  I say cold, relative to the warm summer air.  I would guess mid 20s ambient, the cold spill in the order of 10-15 lower.  There would often be tornados in the area too, although being the UK, they would struggle even to be classified at F0s, more like F-wanna-be-zero.

@casey This reminds me of a recent post from the local NWS office which said that it's too bad that the quantity is convective available potential energy instead of convective available kinetic energy, because the latter would have the acronym CAKE, could be measured in Calories, and would be layered. :)

This is a great answer, though. It might also be good to mention microbursts in it also, as those are usually (always?) associated with CBs and are extremely dangerous to aircraft (see Delta 191 for example.)

@reirab there are always downdrafts associated with the precipitation core of the thunderstorm (and on the flanks of supercells) and these are sometimes microburst strength.  You likely wouldn't be operating near these though (hopefully).  More dangerous are microbursts associated with virga as the surface weather can be nice and the clouds high above the surface.  The virga will cool the air as it evaporates and become negatively buoyant and can produce a microburst in clear air.

Wow! I didn't know CB was so deadly... It is such a beautiful and odd cloud. I have never seen one... And now I really want to not find one. @casey thank you for your answer. As always you provide great content to this site.

@GabrielBrito You should visit the Southeast U.S. in the summer (i.e. now.) We have them pretty much every day.

Why is lightning a threat? Aren't planes supposed to pass through them just fine?

@Mehrdad lightning can puncture small holes in the aircraft skin and while most of the time damage is superficial it can take the airplane out of service while the skin is patched.  There may be more threat within an active lightning storm as flash rates can be very high and multiple strikes are more likely to be harmful than just one.

Since the mechanism of those upwinds has not been explained yet:
A cloud is generated by condensation of water vapour. That emits the energy once stored in the vapour as heat. The heated-up air rises through the cloud, sucking fresh air from below, that again condenses.
That creates a strong upward air current, and depending on your plane, you might not be able to escape it. (There are regularly casualties of gliders and balloonists dying of hypoxia in high altitudes.) However, what goes up must come down, so around those clouds there are strong down-currents. The windshears between up- and downwind can be extreme.

In a sentence, cumulonimbus clouds, aka "thunderheads", are more or less land hurricanes. They are formed when warm, humid air is quickly forced upward into higher altitudes where its water cools and condenses rapidly. This updraft can occur in many ways, as simple as high thermal heating or lateral winds being forced upward by terrain, to "collisions" of other weather events, like a strong warm front passing through an area of low pressure (which will pull in air from all directions, and the only plae the air then has to move is up) or a warm and cold front meeting with the cold air forcing the warm air higher. When this happens, a lot of moisture can suddenly no longer remain in vapor form, and condenses into rain, but the updrafts can keep the rain in the cloud for a while, letting more and more liquid form.
Thunderheads pose several dangers at practically any altitude. At the surface, first is the torrential rain, which can reduce visibility to zero in the blink of an eye even for drivers on roads. Then you have the high straightline winds which can force vehicles with bigger cross-sections, like vans, box trucks and semis, off the road. Third is hail; the strong updrafts and downdrafts combined with the rapidly cooling air causes ice chunks to accumulate layers as they're tossed around by the air currents within the cloud, until they're finally too heavy to remain aloft and fall as hailstones. Here in North Texas, hail up to grape size is common with these storms, and the last really big storm we had produced reports of softball-size hail, which will destroy cars, punch holes in roofs and most definitely kill unsheltered people and animals. Last, and worst, is what happens when these strong updrafts and downdrafts are coordinated enough to form a vortex. Gyroscopic precession and the Coriolis effect will kick this vortex on its side, and you get the strongest weather event that can form over land; a tornado. Even the weakest of these are deadly to anyone who doesn't take shelter in a reinforced interior or underground space.
For aircraft, you have all these hazards and many more. First is the severity of the updrafts and downdrafts; if the currents inside a thunderhead can keep a chunk of ice the size of a softball aloft, just think what it'll do to your little Piper Cherokee (or even a 747). Second is icing; as your plane is getting tossed around, the same near-freezing water condensation that forms hailstones finds the ultra-low-pressure environment over the top of your wings' leading edges simply irresistible. Third is debris; if there's an active tornado or even high straightline winds associated with this event, not only will you have ice flying around, but dirt/sand, rocks of varying sizes, tree branches, all the way up to Dorothy and Toto. Even planes with a military pedigree, like the P-3 Orions that are used to track hurricanes, can't survive this kind of onslaught.
Don't go anywhere near a thunderhead. Just don't. In fact, if you're a private pilot, don't even take off if there's a thunderhead anywhere near you, and if you're flying cross-country and see one, get on the horn with ATC immediately and request information on its course and speed and what you can do to avoid it. For pilots of small unpressurized craft the answer will usually be to put the storm front on your tail, open up the throttle and find the nearest airstrip that can take you.

The "see one" is a bit of an exaggeration, as in the western US you can easily see them from 100 miles away, when at altitude.  E.g. from about 10K ft over Sacramento, I'd see storms out east of Reno, with the airports there being in clear weather.

Your first paragraph isn't entirely correct.  Thunderstorms can initiate in many ways and neither a cold front or warm front is necessary (and neither can collide with the jet stream, being separated vertically).  Thunderstorms can get started by anything that pushes parcels to their LFC, which can be forced lifting along a cold front or any mesoscale boundary (gust fronts, sea breezes), dynamically by gravity waves, thermally by solar heating, orographically by terrain and winds.  You can initiate severe convection with nothing more than localized heating.

@jamesqf - Fair enough, but if you're flying a smaller unpressurized plane the range at which you see it would be reduced. The fronts that produce thunderheads, at least in the Plains states, can stretch for hundreds of miles and move at up to 35mph. Yes you can outrun them in a small prop, but only if you planned on flying directly away from them in the first place; if you plan on going around, you have to be sure that first, you can get past where the storm will intercept your track before it gets there, and second, that the storm won't continue to develop beyond its current size.

There are two primary reasons:

Cumulonimbus clouds are formed by rising water vapor droplets which cause powerful upward air currents; obviously this creates very unstable and turbulent air which could be detrimental for an aircraft.
Torrential rain, frost and lightning can be dangerous for a numbers of reasons - but mostly for icing on aerodynamic surfaces and pitot tubes becoming blocked.

The droplets don't cause the rising air. It's the other way around. But, yes, it is extremely turbulent and unstable.


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Can an Autogyro with wings survive a rotor mechanical failure? Will it be safer?
I'm not an expert but as I understand autogyro sustentation relies on the rotor. If the rotor breaks, the aircraft will fall as a rock to the ground... But If the autogyro was built as a tractor design and had wings as the first cierva autogyros did: Would it survive to a rotor destruction? In case of rotor breaking the pilot maybe has a chance to glide and do an emergency landing. Is it safe to build an autogyro with wings? Does it have an increased operational cost?
Note that having wings add the  incovenience of being afected more by the turbulences and wind.

If the rotor breaks at speed it'll probably shake apart anyway...

Helicopters don't seem to have that problem very often

@DanPichelman That's because rotor failures on helicopters are extremely rare.

That is a very broad question and covers many topics, but I will try to answer as best I can and not miss anything.
A quick note on the wings.  Adding wings as a safety aspect to the aircraft kinda defeats the purpose of an autogyro.
Would it survive to a rotor destruction? The likelihood of an autogyro surviving rotor destruction is extremely remote. Best case scenario would be the entire rotor assembly detaches from the mast and flies away from the aircraft.  Worst case scenario only 1 or 2 blades fly off. (Honestly would be more likely to happen IF rotor destruction were to take place.)  In this situation the imbalance in the rotor would be so violent that surviving, let alone actually flying, an autogyro in such a configuration would be truly "Hand of God" type miracle.  If you want to see something similar try removing a blade or two from a fan and you will see this imbalance in action.
Taking the best case scenario could the pilot make an emergency landing? Yes, but their options would be limited, assuming you can recover AND get into the best glide configuration by 5,000' AGL you would likely have less than 8.3 minutes to find a field and get ready before landing. Lower altitudes will provide even less time before contacting the ground.  (This number is only approximate for a 9.3:1 glide ratio and it would be unlikely for wings on an autogyro to even do that well.)
Is it safe to build an autogyro with wings? Yes, as your picture shows it does work.  A few companies today, such as Carter Aviation Technologies, use that design albeit with much shorter wings designed to work in conjunction with the rotor.
Does it have an increased operational cost? Possibly.  Those smaller wings mentioned in the paragraph above actually increase the efficiency and reduce the operational cost.  The problem is that those types of wings are almost entirely useless without the rotor.  Wings big enough to provide a decent glide ratio and time for the pilot to react to rotor destruction would end up providing more drag and require a larger engine to overcome it thereby increasing the operational cost.
As far as turbulence goes, you could see more turbulence with larger wings but with small wings like on the CarterCopter, the additional turbulence added to the aircraft because of the stiff wings would be minimal.

In a test of a Pitcairn autogyro prototype, one of the rotor blades broke off mid-flight. This caused violent shaking and the pilots bailed out. However, despite the vibration, the rotor was still producing sufficient lift, and it flew in a gradual spiral and landed itself in a field with minimal damage.

It's amazing that happened and the aircraft didn't spiral completely out of control. (Not something I'd count on though!)

Sure those wings would help, but if the 'mechanical failure' of the rotor involved an important imbalance, such as the loss of a blade, the machine would be difficult to control, wings or no wings...
Besides, those wings in the early autogyros were there not for extra lift, but just for aileron roll control, before the introduction of the tilting rotor head, that allowed full control of the aircraft in all axes.


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What causes the phenomenon that pilots don't believe their instruments, while they're working well?
I read in a comment on another question that pilots not believing their instruments while they work perfectly well is common in aviation:

The flight leader reported that his compasses had failed [...] but there is a thin line between believing that your compass has failed and it actually failing. Not believing the instruments, when they are working perfectly well, is a well known phenomena in aviation.

Why is that?

Which question? In which situation? Maybe you're referring to spatial disorientation?

The same reasons than believing pixels of square B are lighter than pixels of square A. Our brain filters and changes perceived reality to match with what we have already learned, before processing the information further. See Empirical theory of perception. Most of the time you cannot prevent this to happen.

So it isn't a phenomenon occurring more in aviation than in other areas?

@MarcoSanfillipo-I read it in a comment to my question concerning the Bermuda triangle.

*occurring more in aviation than in other areas". Probably not, stronger coupling is found in things like existence or absence of religious beliefs for example.

@descheleschilder Ok, then maybe you can add a link to the question :-)

Did you ever see a magic show where the performer did something you knew couldn't possibly be done but you saw it with your eyes and were amazed anyway? Same principle.

@RonBeier- Not really. There is no trickery involved in the case of the pilots reading their instruments.

Human decision making is an entire field of psychological research and there are many, many studies and books about it. Yet for all that we really don't know exactly why people make the kinds of mistakes they do, so I will summarize the theoretical work that I personally have studied, which are Heuristics and Cognitive Biases.
The theory is that human brains simplify decision making by developing Heuristics, which are essentially algorithms which allow for quick and efficient information processing. Think of it this way; you don't have time to analyze every situation from the ground up. Imagine if every time you walked up to the cashier in a store, went to cross a street, or from a piloting perspective became too close to another airplane you had to examine it from first principles! It would be slow, exhausting, and possibly dangerous. Heuristics are the brain's sophisticated way to shortcut that so that decisions can be made fast, they are developed through personal experience, second-hand experience, and training.
The problem is that heuristics are prone to biases and errors of logic. Heuristics can be developed which get to the wrong result with a given set of information, these lead people to making the wrong decisions, interpreting situations incorrectly when thinking about it anew would give an entirely different result. Ambiguous data can lead to the wrong heuristic being used, several options being available forces the brain to choose the best one.
I think heuristics theory goes a long way to explaining some of the common mistakes that are made in the cockpit, this is from my study of the material and from time in the cockpit, what is not that well understood is how stress and motivational factors can influence them. There's also the role of biases, which cause deviations from logic and good decision making. Some relevant ones are:

Selection bias, where someone cherry-picks what they want to see so it fits their view
Confirmation bias, where someone ignores things that don't fit their view, this is also known as expectation bias
Attention Tunneling, where someone becomes fixated on one thing and ignores others

My personal view on this is that the human brain has a tendency to force heuristics to fit input when it is ambiguous, especially in busy or stressful situations. This can be a good thing as it makes people act when they might otherwise not have, but people tend not to notice when the brain's developed ways of interpreting information don't fit the context or arrive at an obvious error. We won't like the feeling of being wrong or we are busy with other things, so we don't re-evaluate information. Sometimes people die because of that.
This is why airlines have re-curring situational training, and why that training is so incredibly important for safety. They train pilots to match what they see and feel to sets of actions so that the right decisions are made quickly.
EDIT:
There was a comment asking whether these effects could be contagious, the answer is yes, sometimes incorrect ideas get passed along, and if they don't get challenged it can lead to disaster. Some of these effects are:

Availability bias, where an event happening to one person makes another think it is more likely to happen to them. One pilot's instrument failure makes another think theirs did too, even though it's not true
Authority bias, where someone believes something is true when the source is a famous or authoritative figure. A captain telling a FO that an instrument has failed makes the FO believe it because they're the captain
Groupthink, where social pressures to conform or avoid dis-harmony make people buy into bad decisions

Has it been demonstrated that those errors are contagious? It seems that I've seen several cases of spatial disorientation where one pilot loses confidence in his instruments and says, for example his AI has failed, then the second pilot, paradoxically, believes that his AI has also failed.

It absolutely is contagious, there are a few reasons. I'll edit as it's too long to put in a comment.

The best answer!

I have not heard of instances where a pilot did not believe his instrument was working properly when in fact it was.  I do know of times where a flight crew either did not pay attention to their instruments and trusted their vestibular senses as to the orientation of the aircraft or became so saturated with other cockpit tasks that they ignored what the instruments were telling them.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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What makes it so hard to land on an aircraft carrier?
I have heard it is very difficult for a pilot to land on a carrier deck.
I have read this question but it didn't really give me a sense of the challenges that pilots face.
This question lent me the insight that metal decks, themselves, have different properties (that I should have considered)... perhaps friction, changes due to thermal shifts (that asphalt does not exhibit), perhaps it 'gives' differently under touch-down pressure.
Can someone paint a more-complete picture?  I'm sure there are also other factors, besides that the deck is moving.... but even then - perhaps there are 'different kinds' of movements of the deck that I haven't considered.

The answer can be summed up in two words:  It's moving.

@Lnafziger then why the metal runway for practice?

I'm not sure that's really what that was for, especially since for practice you would need arresting gear and a lot more stuff....  But in any case, the "hard" part is that it's moving...  Moving Left, Right, Up, Down, and towards you...  All at an unpredictable rate/direction.

@Lnafziger I suspect what they're really trying to get you to practice at Bogue Field is catching the arresting wires (if you look near the touchdown zone markings at Bogue Field you'll see ground arresting gear) - that's got to be much easier to do on land than it is on a real carrier even with calm seas, and one you can do it there they can let you try the real thing :)

The surface plays no role in braking.- you either catch the wire or you are off again. The wheel brake simply does not come into play here until taxying.

The very title of this question gave me a good laugh. But I know you want actual reasons behind it and not @Lnafziger 's sass.

@Jhawins yes.  I already had quite a visceral impression of the issues of a moving deck.  I wanted to ask in order to exercise the site and get a full picture of the other issues involved.  The thing about a metal practice runway just gave me the impetus to ask.

try it in fsx...

One thing that has to make it harder is that it's much easier to hit the control tower on landing than at most airports.

Edit
Since another user, with actual carrier experience, has given a detailed answer, please refer to his answer.
It now appears that a good part of my answer was incorrect.  As I wrote in the beginning, my answer was based on flight-sim experience, and reading, but nothing formal or official.
I'll leave my answer up, solely for historical reference, unless the better answer gets accepted.

I've never done it IRL, but read about it lots, and Flight Simmed it many times, so I'll take a stab.(until someone who has actually done it says better)

Glide Path
When landing on a fixed runway, your glide-path is pretty much right towards the end of the runway.Its not like that at all on a Carrier.  From up high, you are actually aiming for a point in front of the carrier.  You're aiming for where the runway will be in 30 seconds.   As you get closer, the carrier moves closer into position.  But still not entirely in position until the last second.   So you're always aiming for an invisible/imaginary point where the runway will be at the last second.
This is the best picture I've found of what I'm describing:

Notice that the flight path indicator (the little circle in the HUD) is well beyond the front of the carrier.  If this plane was landing on a runway, the flight path would be aimed right at the numbers.
No Flare
In a typical runway landing you flare out just before touchdown, "float" for a second and drop on to the runway.In a carrier landing, you maintain your glide-path attitude all the way on to the deck.   There's no flare or float. This helps you hit exactly the spot you're aiming for (the 3-wire), but in some sense you really are crashing into the deck at a not-inconsiderable descent rate.
Pitching Deck
Remember the glide path to the imaginary touch-down point?  Because the carrier deck can be pitching or rolling in the waves, that imaginary touch-down point is not a fixed distance directly in front of the ship.  As the ship bobs and weaves around, your touchdown point is moving around too.   That makes it even harder to hit the point right.  It can well be at the last second, as your plane is dropping quickly, the deck suddenly jumps up to meet you, making the impact even more violent.
Sideways Movement
The landing part of a carrier deck is the diagonal part on the back of the deck.   It is angled about 20-degrees to the left, relative to the carrier.  But it is moving directly forward with the movement of the carrier.  This means the "runway" is not moving directly away from you, but slipping sideways.

The glide path argument doesn't really hold. There is no back ground reference where you aim at, it's all sea. You will just approach to the carrier as if it was a normal runway. The fact that the ship is moving by about 30 knots makes that it feel as if you encounter an extra 30 knots headwind.

I can't imagine that the aircraft carrier will be moving towards the landing aircraft. I suspect it will be moving away (in the same direction as the landing plane). But then again, I've never landed on an aircraft carrier :-)

@PhilippeLeybaert:  Did I write anything to indicate the boat would be moving towards the plane?  That is not my intention.  You are correct that they'll both be moving in the same direction.

What about the size. It´s a tiny piece of ground for a jet.

@abelenky It depends what you meant by in front :-) From the standpoint of the pilot or from the standpoint of the carrier? :-)

@PhilippeLeybaert:  See the picture that I added to the question.  From both the perspective of the Pilot and the Carrier, the plane is aiming for a point in front of the boat.

Something else that makes transition from a runway to a flight deck difficult: you're just about landing on the nose gear (which is very beefed up in carrier aircraft), rather than flaring to touch down on the main gear. Naval aviators (they disdain the term "pilot") have a saying, "flare to land, squat to pee" to indicate what they think of Air Force pilots :).

Actually, aside from your lineup, you don't aim for any part of the boat--that's called deck-spotting.  Your glide path should be controlled by the ball, and you'd like to see it either centered, or slightly above the datums.

Just a comment on "sideways movement":  While it is technically true that the ship is "slipping sideways" to the right, this is perceived by the pilot only as a slight crosswind.  Most pilots would consider a crosswind within +/- 10 degrees of the runway heading as negligible.  Also, the pilot does not aim for a point in front of the landing area.  See my answer below for more perspective on this...

P.S.  In the day time case 1 pattern if you were aiming for where the ship will be in 30 seconds you would be waved off for being long in the groove.  Target straightaway time to keep the pattern tight for efficient recovery is only 15 to 18 seconds in the groove!

I have no problem marking @MichaelHall as a the accepted answer, but I'd like to see someone edit-in other context to make his answer comprehensive —  since it sound like you'll delete yours once I switch.

First I would like to dispel the common misconception that the ship’s forward motion relative to the water requires the pilot to aim for a point forward of the intended point of landing.  It does not.  The approach is flown the same whether the ship is stationary or moving.
For any pilots out there, do you aim for a different landing point on the runway depending on the wind?  Probably not, you shoot for the landing area and adjust the controls for the effects of wind to arrive in the same spot every time.  If winds are calm you need less power to maintain glideslope, if winds are strong you will need more power for the same glideslope.
It is the same thing at the boat.  We don’t care about our motion relative to the water, only the ship and the wind matters.
Now, I flew steam gauge Prowlers so I can’t speak to the HUD, but my Hornet friends would tell me that they initially put the velocity vector in the notch between the end of the landing area and the port side forward.  So, this is a little forward of the intended touchdown point, but not nearly as exaggerated as the screen captures I've seen depict.  The pilot should then fly other visual cues to touchdown.  I would presume that as the computer stabilized and updated as they came down the groove that the pipper would settle right in the landing area.
However, without the benefit of a HUD there is zero pilot adjustment made for ship’s forward motion.  And even with this tool the flight computer should adjust for the effect of wind and put the pipper in the landing area where the plane is headed, right?
Bottom line, we don’t care about or even notice the aircraft or ship motion relative to the water during final approach.  Our perception, and the net effect of the ship’s forward progress, is on wind only.  We are trained to fly glideslope, line-up, and aircraft angle of attack all the way to touchdown.  Overthinking things only leads to confusion, and spotting the deck is highly discouraged.
There are a few caveats to that last paragraph concerning ship motion:  We make note of natural vs ship generated wind.  When there are whitecaps and little to no ship’s wake we anticipate natural winds right down the angle.  If the sea is calm and there is a boiling wake behind the ship we know the ship is steaming hard to make wind, so there will be a slight right crosswind and some turbulence from the island.
Pitching decks have been talked to death so I won’t expound on that in this answer…
And finally, the ship may turn during your approach.  They really try not to, but sometimes they do, and it can make chasing line-up a bit sporty!
To summarize and answer the main question, landing on an aircraft carrier isn’t inherently all that much more difficult than other aviation tasks that require a high degree of precision.  I have been into a pretty tiny little runway, and been bounced around by wicked crosswinds in light civil aircraft and it put a very similar level of strain on my pilot skills.
A big part of it is mental.  There are plenty of good pilots out there who can fly an ILS on the rails that would probably make it in Naval Aviation.  It just takes a level of commitment, training, and discipline to succeed over a sustained period time.
P.S.  I have 300+ traps and was a wing qualified LSO in case anyone is wondering about my credentials.

Landing point is extremely small for the speed the aircraft approach at for landing.
Landing point pitches up and down.
Landing point is not stationary, but is a moving point.
The metal underground won't matter. It will have a special friction surface. It is very sturdy. The cable will stop the aircraft.

The landing itself isn't difficult; what is difficult is precisely tracking a moving certerline and glideslope right down to touchdown within a small area of the deck in order for the jet's tailhook to snag a cross deck pendant.  Get too high on the approach, you will miss the wires (bolter) and have to go around.  Even worse is a low approach where there is a risk of smashing straight into the back of the ship (rampstrike).  Add to this that most tactical aircraft are flying the approach at 120-140kts, giving very little time to correct errors as the jet gets in close to the boat.  The approach gets even more difficult when the ship pitches and rolls in rough seas as well as at night or in marginal weather making an instrument approach, where visual cues are diminished or nonexistent.
What it takes is an ability to fly the approach with very little deviations combined with rapid small corrections in position, speed, angle of attack, etc. during the approach.
Great video of CAW 11 aviators aboard the Nimitz off the coast of Australia in Oct 2004 attempting to trap at night in rough seas with swells +/-30 ft.

The reason it's so hard is mainly because the touchdown zone is very small, especially for such fast and heavy airplanes. There is also the stress of knowing that if the plane strays outside of the tiny landing area it can impact other aircraft, or parts of the ship.
Ship movement is a factor, but not as much as you might think. The optical glideslope system is gyroscopically stabilized (or manually stabilized in more severe conditions), so theoretically the pilot just has to fly the procedure. The system is so precise that it even adjusts for the size of different aircraft so that airplanes of all types touch their tailhook in the same place.
The landing gear shock absorbers have a long range of travel and are unsprung. So when the plane touches down a lot of energy is absorbed by the struts without bouncing the plane back up.  But even these struts can only compensate for a limited descent rate.  It's very important that the wheels touch down on a low approach, because if the tailhook engages in flight the plane will likely be irreparably damaged, with possible injuries or loss of the crew.


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Changing the missile's flight speed
I am interested in the range of velocity changes of missiles. Planes have a minimum speed set equal to the landing speed, helicopters also have a set speed - this is zero, but what about missiles? Anti-ship and anti-radar missiles have a well-defined trajectory, however, their maximum and average speeds are determined in the documentation. Which traffic sections do they correspond to? And is it possible to somehow estimate the minimum speed of missiles? Example of missile flight sections in the picture.

Dear downvoter, since user66348 is a new user, would you consider adding a comment to explain why you think this post is sub-standard? We can't expect new contributors to be perfect from the start, and without taking the time to explain how posts can be improved we can't expect the quality to magically become better either.

For users unable to read the image: it shows the typical flight trajectory of a Harpoon anti-ship missile. The flight is split into the phases "Start", "Cruise", "Target search and acquisition" and "Self guidance".

Using the phrase "minimum speed" without defining what this  minimum is for! Minimum for maneuverability?, for 1 G level flight?, for closure on a t600 kt target ?, every one of those could be different.

Pretty much all missiles ignite a solid-rocket motor called a booster rocket shortly after launch/deployment/firing. Typically, the missile will reach its highest velocity and energy state, shortly after burnout of this booster. After this point, it will lose velocity because of air-drag, or because it lofts its trajectory for various reasons.
Having said that, there are a lot of exceptions. For example, most cruise missiles have some sort of air-breathing motor (e.g. the Tomahawk has a turbofan motor), which will propel the missile. In that case, the booster rocket is only intended to bring the cruise missile up to sustained flying speed, such that the motor can ignite. An interesting application is that of Ramjets: These engines need a certain speed (e.g. Mach 3) to ignite. After ignition of the motor the missile will accelerate even further. A good example is the X-51 waverider experiment in which a Scramjet (a supersonic Ramjet) was tested.
Other missiles feature a sustainer rocket engine, in principle a second rocket motor which burns slower but longer, and keeps the speed of the missile up. Especially air-to-air missiles loft their trajectory directly after launch in order to fly into thinner atmosphere. When these missiles descend again, the speed can be even higher than shortly after launch.
Missiles also do have minimal speed, however this is a bit harder to define as they loose their ability to maneuver gradually with decreasing airspeed. The question is therefore not the minimum speed but rather the mininum maneuverability you are willing to accept.

First: the numbers on that picture indicate range (in kilometers) and altitude (in meters), not speed.
A missile typically does not actively regulate its speed It's turned on, and when the fuel runs out it coasts. Depending on the power of its engine, range to target, flight path, and atmospheric conditions it may or may not reach its maximum aerodynamic speed during its flight time (most will, as most will boost to that speed very rapidly).
Of course a missile, like any object, will bleed energy (thus (max attainable) speed) when turning or climbing and may gain some when diving.
I've not heard of missiles with speed brakes (the only way to actively influence a missile's speed, especially for a missile with a solid rocket motor rather than a turbojet motor like Harpoon) but they may exist (there are bombs with speed brakes to slow their fall for example).

Re : "  it may or may not reach its maximum aerodynamic speed during its flight time (most will, as most will boost to that speed very rapidly). " -- I'm not sure what this means.  Is this a statement that pertains to the specific motor installed?  Are you essentially discussing whether or not forward acceleration has dropped to zero before the end of the motor run?

@quietflyer nope, just that it may hit its target or otherwise stops to exist before its motor runs out

is it possible to somehow estimate the minimum speed of missiles?

Yes, if one treats them like aircraft.  Weight, wing area, and coefficient of lift should yield an estimate for minimum airspeed.
However, in application, missiles are built for speed, rather than efficiency, although, as pointed out by U flow and Jim, high subsonic cruise missiles do exist.
And, of course, we have torpedoes, which essentially are underwater "airships", using bouyancy as a source of lift.
But I doubt the crew of the "Craptonesque" could stand the suspense of waiting for anything slower than high subsonic.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Why is Python used on aircraft although it may not be certifiable?
I recently had a discussion with people who were active in the aviation industry and told me that one of the main languages/tools they use is Python.
On the other hand I have always known that people avoid C++ or eg Linux due to certification reasons for avionics. Certification is also one of the reasons you don't see AI and computer vision in C++ on aircraft. Yet, those people use Python all the time.
I didn't have (and never will have) the opportunity to ask why and for what they used it. Could someone explain why and for what people would still use Python although it may be very difficult to get it certified?

there are more computers on a plane than avionics, especially on a airliner. also there are more computer in the industry than ones on a airplane. they can write their website in php, their booking server in cobol, infotainment in java, or data base in sql, whatever.

Also, just because they use it doesn't mean they use it on the plane. I work on (less critical) embedded software and the whole test system is written in Python even though the actual software is in C.

What do you mean by certified?

This is begging for a 'snakes on a plane' joke....

@LangeHaare Pretty much everything that goes into the design of an aircraft has to be certified by the relevant aviation authorities before the aircraft is allowed to be flown legally. Safety-critical systems - such as the code that runs the flight controls - require quite stringent certification standards to be met.

To add a further comment about C++, Lockheed specifically wrote a coding standard for its use on the F-35 program: http://www.stroustrup.com/JSF-AV-rules.pdf. So yes, C++ is used.

"...told me that one of the main languages/tools they use is Python..." But for what? The question should really be extended to include that vital information. Otherwise I fear it will be too speculative.

@reirab why would c++ and linux be certifiable? Seems reasonable to me to be able to certify the software.

@tuskiomi It depends on the type of code in question. Using Linux on the passenger in-flight entertainment system? Not a problem. Using it on the computers that run the fly-by-wire system? Much bigger problem. Among other things, non-determinism will be an issue. Timing is inherently non-deterministic on an OS with preemptive multitasking. RTOS or bare metal are typically the only viable choices for such scenarios. Dynamic memory allocation is also inherently non-deterministic (unless you know exactly every allocation that will occur and in what order.)

Just because aviation developers use Python, does not mean that Python actually goes flying.
Lots of aviation development is about testing, stressing, validating, analyzing, and documenting the code that does go flying.
Python is an excellent language for all that validation work, even though it stays on the ground.

Yep, Python is a common scripting language used with automating test equipment. The primary languages that I'm aware of that actually fly are Ada/SPARK, C/C++, and assembler

@selectstriker2 C++ you sure about that? I was pretty sure companies had some issues with certification for that language as well. As an example: People doing AI and computervision for UAV's write all their code in plane C rather than using the well-known opensource libraries like openCV.

It isn't the language that causes certification issues. Things like dynamic memory, exception handling, inheritance, and function overloading can increase the amount of certification (verification) work needed. The biggest certification burden is when you use an RTOS rather than write for bare metal.

I'm sure there is plenty of C++ being used on DO-178B/C projects at Level D or Level E.

And just because code is flying does not mean it's safety critical. These days people are using iPads as part of their avionics setup - IPADS!! But these are normally used for navigation and charting - the iPad never gets to control any control surfaces or landing gear or anything mechanical

There are comprehensive guidelines puiblished for software development in C and C++. These prohibit using the more "troublesome" parts of the languages. See https://www.misra.org.uk/Publications/tabid/57/Default.aspx. Ada "seemed like a good idea at the time" but it has never become a mainstream language, which means the user base is (probably unsustainably) small - unless you believe it does have a long term future which you want to be part of, you would most likely avoid getting involved with it.

@LandonZeKepitelOfGreytBritn: "Plane C" - is that a deliberate joke? :-)

@psmears Given alephzero's link, there is indeed a subset of C that could be considered "plane C".

As a side note, some of the verification software does have to be formally qualified under DO-330.  The general rule of thumb is that if software automates DO-178 certification processes and the output of the tool isn't reviewed, you need to do a qualification process to prove your software is dependable.

Of course Python goes flying! import antigravity

@selectstriker2 Some languages basically force dynamic memory allocation on you whether you like it or not. Python is one of them.

@PeterGreen Which is why you wouldn't use Python in safety critical applications. I was talking about using C++, which can be used but you need to consider the items I listed.

@selectstriker2 Heh, agreed. The QNX'ers and C/MISRA guys who work in automotive can't even get C++ in vehicles, in spite of considerable efforts. Python? The proposal would be laughed out of the building, since it won't come anywhere near meeting safety specs, certs, etc.

I worked for a avionics sub contractor.  We used C for all controls software and python to Hardware in the loop blackbox test EVERYTHING.  ~80%-90% of all code written was python test code.  Every line of C had hundreds of lines of python testing it.

@selectstriker2 nearly all the language features of C++ over c cause determinism issues.  That coupled with unpredictable and un certified compilers means there is no real point in writing in a language where you need to be constatly vigilant to make sure language features aren't being use.d

As a software engineer who works at a defence company that develops and sells mission critical (but not safety critical) systems, I can confirm that there's a pretty even split between development in Ada (95) for our legacy products and various flavours of C/C++ for our new products. Development in both is of course done to the appropriate standards.
Python is largely limited to plugins for our IDEs or validation and verification activities (being used by both software and systems engineers).

I enjoyed Ada 83 a lot when it was taught in my college, partly in order to create a level playing field for the students. I found that when I put its features to good use my programs were a lot less likely to crash than with C or C++. I find especially C++ extraordinarily toublesome as a language (and I have been using it for >20 years now, and read the last three standards -- ok, maybe that's why). C is not exactly safe but at least a small language which is easy to completely grasp (the language, not the libraries). So is Ada indeed phased out even in avionics? That would be sad.

I've worked on safety critical avionics software for the past 10 years or so, and in that time I've never seen Ada used. I know some large companies may use it for some projects, but it isn't taught in most colleges. C/C++ tends to be the most widely taught bare metal language.

@Peter The SPARK/Ada people claim it sees use in the EuroFighter and Rolls-Royce engines. I really like the idea of language provability, but it definitely seems like a niche feature.

@mbrig I find it amusing that the US DOD developed ADA is being used in the EuroFighter and the British (well, sort of... OK in name only) Rolls-Royce engines.

@FreeMan I'd imagine that EuroFighter and Rolls use the U.S. DoD-developed Internet, too. :) DoD develops a lot of things.

@mbrig Currently working on the Eurofighter so I can confirm, it's all over the Typhoon (and the Tornado). I believe it was mandated by the MOD way-back-when.

@PeterA.Schneider: A major problem with C is that while the Standard notes that implementations often usefully expose documented features of the execution environment in cases where the Standard would otherwise impose no requirements, and low-level programming often requires use of such features, there's no standard means by which code can indicate that it requires e.g. the ability to use relational operations to test whether two pointers identify overlapping regions of storage.  Linear-address systems will generally define a global transitive ordering relation among all pointers...

...but compilers for such systems may sometimes decide that since the Standard imposes no requirements on what happens if code compares two unrelated pointers, they should assume code will never do so.

That's why we test and verify everything, just make sure that the compiler didn't generate machine code that behaves differently than is expected

There are three basic areas of coding for aviation engineers.  Software code that runs on flight computers and other avionics equipment, software that formally verifies and creates that code, and scripting to automate informal work tasks.  Python has different use cases in all of them.
First, for actual on-airplane software. There are different safety levels here and different required levels of testing.  Python would be a nightmare to certify for a critical display, autopilot, or ground-proximity warning unit. C's lack of object-oriented programming and complaints when you abuse variable types may be annoying, but they also lead to easy verification that the software isn't doing something wrong behind your back. On the other hand, I've heard of noncritical systems like in-flight entertainment and maintenance even using systems like Windows NT.
Code generation and formal verification (the kind that's documented to prove to certification authorities that you won't, well, kill anyone), do have to be formally qualified sometimes.  You can't just write a Python script to test all your software by simulation, formal methods, etc, then say to certification authorities that your Python script showed no problems.  To be more specific, DO-330 provides guidance that if you're using a tool to replace DO-178 processes (like testing, code generation, or configuration control), then that tool needs to either be formally qualified or its output needs to be checked (yes, even if the output is more fool-proof then a human doing the same analysis).
Finally, a lot of engineers' jobs involve scripting, and there are few langugages more popoular right now for scripting than python.  By scripting I mean solving problems like:

What issues am I working on in this area?
How do I add a description to a hundred files at once?
Is this criteria statistically different from that criteria?
How can I pull hundreds of lines of data from our database and dump it into a spreadsheet for my project engineer?
How can I email my boss every day asking for a promotion?

In these non-critical but quotidian affairs, python scripting can help wrangle lots of complex or repetitive tasks and make them manageable.

I've seen more than a few airport terminals running Win NT - you can tell by the BSOD! (Yup, I've seen a few.) Of course, that's aviation related, but not aircraft specific.

For sure we spend a good chunk of time writing fancy Excel spreadsheets full of VBA to process data!

...hacks away at that promotion script

“C's lack of object-oriented programming and complaints when you abuse variable types may be annoying, but they also lead to easy verification that the software isn't doing something wrong behind your back.” Um... C is horrible for verifying anything, you really want a stronger type system for that. Java, C++, obviously Ada all have a better standing here, not to speak of the really strong type systems that languages like O'Caml, Haskell or Idris offer. And even Python is arguably safer than C because its type system is stronger.

(I suppose you're right though that C code which essentially uses the Fortran77 subset of the language can be verified quite well, but it's extremely painful to write.)

I like how you put "How can I email my boss every day asking for a promotion?" as a problem that needs a script to solve. Make sure that in those e-mails you point out the virtues of automation. :-)

@leftaroundabout Yes, C has plenty of room for errors like NaN handling, initialization, and memory structures, but typically code generation for those is set up consistently enough to avoid issues (like avoiding dyanmic allocation and protections against divide by zero).  OOP and loose typing, on the other hand, requires lots of complex structural coverage testing because its possible what you think is a Foo is actually an insidious Bar. See CAST-17 for example.

@CodyP well, loose typing is what I mainly meant by “C is horrible for verifying anything”. Again – true is, as long as you basically just write Fortran77 in C, it is reasonably rigid. But as soon as you want to do any sort of polymorphism, C doesn't help you at all and you have to go through void* which is about the loosest typing you can get. And without any polymorphism, it is very difficult to adhere to DRY, which in principle is very desirable for safety.

C++ OTOH allows lots of code reuse through templates, which doesn't rely on any dangerous subtyping and is completely verifiable at compile-time. And the Hindley-Milner languages generally resolve all polymorphism at compile-time, and never do any implicit coercions at all. About Java or C#... I'm not sure – they certainly aren't the safest option, but at least they're designed upfront with awareness of OO subtyping and its possible security ramifications.


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Can you identify this airplane?
Im thinking the window sequence and the shadow (possible a prop?) Might be your best help. My dad bought this photo and him nor I can figure it out. I work at a dang airport, too! TIA.

I don't suppose you can make out any part of the tail number up close? That would ease in cross-checking the proposed answers.

It's possible that there is a caption or some other traceable information on the back of the print.

It's most likely a Boeing B-29 Superfortress. It was a strategic bomber used by the US in the Pacific theater of World War II. The lower row of four windows and then another further aft matches pictures of the B-29. The "U.S. AIR FORCE" markings are a post-WWII style.

Source
It's also possible that it's a B-50 Superfortress. This was an upgraded version of the B-29 with new engines and other changes that are hard to see in the picture. Only 370 were built. Although it's not clear when the picture was taken, and only 5 examples of the B-50 still exist. The B-29, on the other hand, has way more.

As another fun fact, only two of either type are still able to fly.  Both B-29s, one named "Doc" and the other named "Fifi".  FIfi has been touring the country for years (I'm not sure if Doc has started doing that yet), and you can get a flight on one if you have the cash.

I've not found been able to find any photograph online of a straight B-29 with the "U.S. AIR FORCE" markings in the position shown in the photo in the question. KB-29s and B-50s appear to have been painted that way.

@DavidRicherby yeah, most don't have that scheme. But this site has pictures of a bunch of surviving examples, and four of them have the large lettering.

@fooot Ironically, I might have actually seen one of those... Though it doesn't seem to have the lettering any more. (Not that this is relevant; you've clearly shown that there have been B-29s with the lettering.)

Interesting. We head a B29 here at KLZU for a week or so, I saw it flying today near KPDK. It's a huge aircraft. Not sure if it was "Doc" or "FIFI", could not get the right angle on the aircraft to view the tail numbers sitting at the airport.

Boeing typically has the tight airforce markings near the nose. The photo bears heavy resemblance to the kb-50 as its lower nose portion fit the look when you zoom in on the OPs image you can see the window matching more then the kb-97, was just so big..
KB-97

KB-50

Either way they are both variants of the previous answer.
turret and no turret comparison images below.

Why specifically the tanker variants (KB-xx rather than B-xx)?

I am categorically leaning towards the KB-50 as a match.

The B-50 has a turret on the upper forward portion of the fusalage. The OPs image is lacking the bump that would show a rise to the 50 cal weapon system. The increase tail height was a modification from the B-29 to the B-50. At this point with the information that has been presented, we are as close to a match as we can get. Now if the OP could post a date of the photo and who took the photo that could help us narrow it down to the era. Judging by the image quality and that it appears to be in sepia, I would say it is a more recent photo. Older prints would have a more grainy appearance

It's not clear that the turret would be visible from the angle the photograph was taken from, but I see your point.

I will add some images to my answer.

There's also the point that the only surviving complete examples are KB-s and WB-s so, if it is a modern photograph, it couldn't be straight-up B-50. But I'm not convinced that the photo is modern: very good low-grain film has been available for a long time. And the photo in the question is taken from a much lower angle than the examples you've added. Anyway, +1 for your answer. I don't know if it's correct but it's certainly plausible and well-researched.

If I were to guess I'd say the picture is of the B-50 at the Pima Air Museum.
http://s10.photobucket.com/user/deattilio/media/Arizona%2008/Pima%20Air%20Museum/IMG_3206.jpg.html
https://www.flickr.com/photos/golftwo/4510556800

The blind windows show that the plane was decommissioned a long time before the photo was taken. Good guess! +1

Looks like that plane has now been restored to its original shiny splendor.

This page is about the restoration is dated April 8, 2014 and says the restoration took six months. Thus we know that the OP's picture was taken before October 8, 2013. :-)

Definitely a Boeing B-50, as the nose is similar to both the B-29 and B-50 (but not the KC-97 or C-97), while the extra tall fin eliminates the B-29.